Device warning and protecting against overvoltages especially for electrical shavers operating under two voltages



@en 9., i969 M. M. A. TROUILHET 3,483,545

DEVICE WARNING AND PROTECTING AGAINST OVER-VOLTAGES ESPECIALLY FOR ELECTRICAL SHAVERS OPERATING UNDER TWO VOLTAGES Filed March 28, 196'? MNE): 70K

MALI/ms mii/,fm Auf/,UE WMU/Mfr United States Patent O rut. ci. one 21/00 U.S. Cl. 340-248 4 Claims ABSTRACT F THE DISCLOSURE A protecting and warning device against overvoltages resulting from faulty connections, especially for electric Shavers operable at two different voltages, said device being characterized notably in that it comprises a sensorial signalling system, such as a lamp liable to be actuated only when the apparatus is supplied with an excessive voltage, for example substantially twice its normal supply voltage.

The present invention has essentially for its object a device warning and protecting against overvoltages resulting from wrong connections or switchings, for electrical domestic equipments operable with at least two different voltages, of the type comprising two associated electrical circuits designed to be connected in series when the apparatus is supplied with its highest voltage, or in parallel when the apparatus is supplied with its lowest voltage; the invention relates in a more particular way to warning devices of this type for electrical shavers operating at either of two voltages.

As a matter of fact, it is known that a great number of electrical domestic equipments are designed in such a way as to be connected to the mains supply network as Well, for example, with a 120 volts tension as under a 220 volts tension, these two voltage values being the most currently used in the local district areas of electrical supply. This possibility to adapt the' equipments to two dif. ferent voltages, one of which is substantially twice as great as the other, is usually obtained by dividing the electrical components of the apparatus in two associated circuits supplied under constant voltage (the lowest of the two intended voltages), being only careful to provide a commutator or switch which connects both circuits in serie's when the apparatus is supplied with its highest voltage, and in parallel when the apparatus is supplied with its lowest voltage.

A correct supply of the apparatus is hence submitted to a correct commutation or switching performed by the user before' putting this apparatus in service. If the user commits a faulty commutation, in particular by creating an excessive voltage in the device, it is Very likely that the apparatus will be damaged. This problem presents a special importance with electrical Shavers, as the user is very often led to utilize it abroad. In this case, the user meets heavy difculties in ascertaining the precise voltage `of the mains supply network at the district area where he wants to connect his apparatus, or again this user may forget to check in every location of his itinerary the correct position of the switch before utilizing his device.

If the shaver which is used is driven by a motor of the universal type, it s possible that the change in its speed consequent to a supply with a voltage which is not correct draws the attention of the user, and that the latter may hence think to switch correctly his shaver before having put the winding of the motor completely out of order.

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On the other hand, if the shaver is of an electromagnetic vibrator type, as the vibrations are synchronous with the frequency of the mains supply network, there is nothing, at first sight, to indicate to the user a faulty switching and in this case, if the shaver is supplied with 220 volts, while' the c-ommutator is positioned for volts, this faulty switching will result in an overheating of the winding which usually leads to a quick destruction of this winding.

The present invention has for its object to avoid these drawbacks by providing a warning and protecting device which affords to the user immediate detection of an eventual overvoltage, and which draws with certainty the attention of the user.

The warning device according to the invention is remarkable notably in that it comprises a sensorial warning device arrayed in at least one of the' aforementioned electrical circuits of the apparatus and which may be actuated when said circuit is supplied with an excessive voltage, for example a tension substantially twice its normal supplying voltage, while said warning device is not actuated when said circuit is utilized with its normal supplying voltage.

According to another feature of the invention, the signalling device is connected in series within the aforementioned circuit, and may for instance be constituted by a lamp, forming a luminous signal, arranged on a location of the apparatus which is immediately visible.

Thus, as soon as the user connects his apparatus, he knows if the latter is supplied with an excessive voltage (luminous signal lit) or if the supplying voltage is not excessive (luminous signal out). In connection with this, it may be noted that if the user does not know the voltage of the district area which is available to him, he may for example place the switch on the lower voltage (for example 1l() volts), then connect his apparatus while watching the luminous signal. If the luminous signal remains out, it means that the voltage is correct (no overvoltage), but if the luminous signal lights up, that means that the voltage of the district area is excessive and in this case the user switches the commutator over to its second position (for example 220 volts).

Other features and advantages of the present invention will appear more clearly in the course of the following detailed description of a preferred embodiment of the invention, illustrated by the appended drawings, which are given only by way of examples and wherein:

FIGURE l is a schematic general view of a shaver of the electromagnetic vibrator type, using the safety device which constitutes the object of this invention;

FIGURE 2 is a side view of the apparatus shown on FIGURE l, appreciably following the direction shown by arrow II of FIGURE l;

FIGURES 3 and 4 are switching diagrams showing how commutator of the apparatus works in both of the possible operating positions;

FIGURES 5 and 6 are wiring diagrams, respectively corresponding to the previous switching diagrams shown on FIGURES 3 and 4;

FIGURE 7 is a perspective view, at a smaller scale, showing the normal position of the shaver in the users hand.

According to the method of embodiment shown in the drawings, it has been supposed that the device protecting and warning against overvoltages, or safety device, which constitutes the object of the present invention, is utilized in an electrical Shaver of the electromagnetic vibrator type, this apparatus being especially exposed and sensitive to such overvoltages resulting from faulty connections and switchings.

The shaver as shown comprises a casing 1 wherein are housed, following current methods, a stationary armature 2 made of magnetic sheets, and submitted to a variable electromagnetic field created by two supplying halfcoils 3 and 4, and a moving armature 5 mounted about an axis 6 and oscillating between the legs of the stationary armature 2. Of course, the moving armature actuates a cutting head which is not represented.

The supplying of the shaver, i.e. of the two half coils 3 and 4 is performed by means of a supply cord 7 (FIG- URE 7) which is connected to two control -pins 8 (FIG- URES l and 2). These contact pins 8 are themselves connected to a switch comprising an immovable portion 9, and a movable portion 10 forming a slider. Depending on the position taken by the movable slider 10, the two half-coils 3 and 4 are either supplied in series (FIGURE 3), or in parallel (FIGURE 4), by means of conductor blades 11 and 12 which secure an `appropriate junction between the four supply contacts 13 to 16 of coils 3 and 4. Thus, it is seen on FIGURE 3, that the blade 11 connects the contacts 14 and 15, and in this case the current running flows successively through the lead-in wire 17, the contact 16, the half-coil 4, the contact 14, the blade 11, the contact 15, the half-coil 3, the contact 13 and the junction wire 18, While it appears on FIGURE 4, that the blade 11 connects the contacts 13 and 14, and the blade 12 the contacts 1S and 16, in which case the current flows successively through the lead-in wire 17 then simultaneously, as these elements are connected in parallel through the blade 12, the contacts and 16, the half-coils 3 and 4, the contacts 13 and 14 connected by blade 11, and, at last, the junction wire 18.

This array is also apparent in FIGURES 5 and 6.

According to the invention, and following the method of embodiment shown in the drawings, a lamp 19 is connected in series with the junction wire 18. It appears thus, that whatever the position of the switch (constituted by the slider 10 moving before portion 9) might be, the lamp 19 is always mounted in series with the half-coil 3.

If the switch is placed in its correct operating position with regard to the Voltage of the district area, the coil 3 is supplied under a constant tension (for example equal to 110 volts), whatever the tension of the supply network (for instance equal to 220 volts according to array Shown on FIGURE 5 or to 110 volts according to the array shown on FIGURE 6) might be.

The lamp 19 is for example of a small-sized filament bulb type, and preferably of the type commonly called wheat grain lamp.

The characteristics of the lamp are selected in such la way that its current consumption be of a negligible quantity (the potential difference neighbouring zero at its terminals), and thus this lamp 19 will not intrude upon the electrical operation of the apparatus. Besides, when the coil 3 is supplied under a normal operating voltage, the intensity of the current traversing this coil 3, and hence the lamp 19, is insucient to overheat the filament to the point of bringing it to its glowing temperature. The lamp 19 will thus remain blank under normal operating conditions. On the contrary, in the case of an overvoltage due to a faulty connection, for example resulting from a supply under 220 volts of the coil 3 (the switch being in the position represented on FIGURES 4 and 6, the voltage of the district area being meanwhile of 220 volts), the intensity of the current flowing through the coil 3 is then suiicient to make the lament of lamp 19 glow, and this lamp lights up. If the voltage of the supply network is called V, the respective supply voltages of the coils 3 and 4 being called V3 and V4, the intensities of the currents flowing through windings 3 and 4 being respectively called I3 and I4, while Vn and In are respectively the nominal voltage yand the nominal intensity by a normal supply of each winding, the intensity of the current produced by the mains network at the terminals of the apparatus and flowing hence through lam-p 19 according to the described array being called I, the differ-Y ent cases which may show up are resumed by the following tabulation:

It may be noted that in the last case, the. user will at once see his mistake, as his apparatus is not working, and if besides he was careful to perform the manipulation indicated hereabove in the paragraph just before the description of the gures, this instance will have few chances to show up. In any case, the user is always immediately informed of any faulty commutation which may happen.

The mounting in series which has been shown is especially secure, taking in account that the device may operate only if the signalling lamp 19 is in good condition. The user is thus protected against a failure or a defect in the lamp which he might have overlooked, the warning and protecting device being then ineffective.

Nevertheless, it is quite obvious that the signalling lamp 19 could be inserted in parallel or in branch circuit with the winding 3 or 4.

Besides, instead of a lamp as a signally device, another sensorial signalling device could lbe used, such as, for example, a sounding warner comprising a vibrating blade which is actuated only if an overcurrent happens in coil 3.

Advantageously, and as shown on FIGURES 1, 2 and 7 of the drawings, the lamp 19 is housed in a hollow 20 which is closed by a transparent or translucent window 21, for example of a moulded synthetic material. The window 21 may be coloured in red and constitute thus a luminous signal when the lamp is lit up. The hollow 20 is located just above the recess 24 wherein the contact pins 8, for connection with the supply cord 7, are housed. In this way, when the user holds the shaver in the hand, he takes it as shown on FIGURE 7, on the side which is opposite to the input of this supply cord 7. Thus, he is indeed not disturbed by this cord. Under these conditions, the window 21 of the signal is immediately visible, and when the user connects the shaver, he cannot overlook the lighting up of the signal 21.

Moreover, the setting up of signal 21 and of plate 22, equipped by the pins 8, is performed especially easily and simultaneously by installing the window 21 and the plate 22 in the respective slits on the half-casings 1a and 1b, as shown on FIGURE 2, when the various pieces of the shaver are assembled within the casing 1. Besides, the casing 1 is covered by a hood 23 which protects the cutting head of the shaver and permits the dismounting and cleaning of this head.

Of course, the invention is by no means limited to the methods of embodiment described and represented which have been given by way of examples. For instance, the signalling lamp may be placed at any visible and convenient place on the casing, for example on the lbottom portion of the casing, near to the cutting head, as indicated by phantom lines in 25 on FIGURES 1, 2 and 7 of the drawings.

What I claim is:

1. In an electric shaver operable from two different voltage sources, one of which is higher than the other and including a motor having a pair of windings selectively connectable in series and parallel depending upon which the voltage sources is connected thereto, bi-voltage switching means for selectively connecting said windings in series and parallel, conductive signalling means mounted in said shaver serially connected to permit flow of current therethrough from the voltage source applied irrespective of the state of connection of said windings in series and parallel said signalling means providing a warning signal without interrupting current flow only if the voltage source of supply is then the higher of the two volttages, and. said windings are then in parallel connection.

2. In an electric shaver according to claim 1, said signalling means constituting a lamp visible illumination of which occurs only when the voltage source supply is at said higher of said two voltages and said windings are then in parallel connection.

3. In an electric shaver according to claim 1, wherein said bi-voltage switching means comprises a slider bearing a pair of bridging members which in one position of said slider bridge the respective terminals of said windings to effect series connection of the windings and in a second position of said slider bridge respective terminals of said windings to effect parallel connection thereof.

4. In an electric shaver according to claim 2 wherein said shaver includes a casing formed of two half shells and having a cavity, contact pins connected to said windings for an electric supply cord, said contact pins being UNITED STATES PATENTS 3,215,894 ll/l965 Haussermann 317-13 FOREIGN PATENTS 1,235,628 5/1960 France.

THOMAS B. HABECKER, Primary Examiner DON A. HART, Assistant Examiner U.S. Cl. X.R. 

